Communication devices such as user equipments (UEs) are also known as e.g. wireless devices, mobile terminals, wireless terminals, user terminals and/or mobile stations. A UE is enabled to communicate wirelessly in a wireless communication network, cellular communication network, wireless communication system, or radio communication system, sometimes also referred to as a cellular radio system, cellular network or cellular communication system. The communication may be performed e.g. between two UEs, between a UE and a regular telephone and/or between a UE and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the wireless communication network. The UE may further be referred to as a mobile telephone, cellular telephone, laptop, Personal Digital Assistant (PDA), tablet computer, just to mention some further examples. The UE may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data, via the RAN, with another entity, such as another wireless device or a server.
The wireless communication network covers a geographical area which is divided into cell areas, wherein each cell area is served by at least one base station, or Base
Station (BS), e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. “eNB”, “eNodeB”, “NodeB”, “B node”, or BTS (Base Transceiver Station), depending on the technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the base station at a base station site. Cells may overlap so that several cells cover the same geographical area. By the base station serving a cell is meant that the base station provides radio coverage such that one or more UEs located in the geographical area where the radio coverage is provided may be served by the base station. When a UE is said to be served in or by a cell this implies that the UE is served by the base station providing radio coverage for the cell. One base station may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the UE within range of the base stations.
In some RANs, several base stations may be connected, e.g. by landlines or microwave, to a radio network controller, e.g. a Radio Network Controller (RNC) in Universal Mobile Telecommunication System (UMTS), and/or to each other. The radio network controller, also sometimes termed a Base Station Controller (BSC) e.g. in GSM, may supervise and coordinate various activities of the plural base stations connected thereto. GSM is an abbreviation for Global System for Mobile Communication (originally: Groupe Special Mobile).
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), base stations, which may be referred to as eNodeBs or eNBs, may be directly connected to other base stations and may be directly connected to one or more core networks.
UMTS is a third generation mobile communication system, which may be referred to as 3rd generation or 3G, and which evolved from the GSM, and provides improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for wireless devices. High Speed Packet Access (HSPA) is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), defined by 3GPP, that extends and improves the performance of existing 3rd generation mobile telecommunication networks utilizing the WCDMA. Such networks may be named WCDMA/HSPA.
The 3GPP has undertaken to evolve further the UTRAN and GSM based radio access network technologies, for example into evolved UTRAN (E-UTRAN) used in LTE.
The expression downlink (DL) is used for the transmission path from the base station to the wireless device. The expression uplink (UL) is used for the transmission path in the opposite direction i.e. from the wireless device to the base station.
Paging is a mechanism for a wireless communication network to initiate setting up a connection with a UE when the UE is in an idle state, such as the so called RRC_IDLE state in LTE. In the following paging is discussed mainly in the context of LTE. The UE monitors so called L1/L2 control signaling to receive the downlink scheduling assignments related to paging. During a paging cycle, a UE is allowed to sleep and subject to only briefly wake up to monitor the L1/L2 control signaling. If the UE detects a group identity used for paging, i.e. P-RNTI, when it wakes up, it will process the corresponding downlink paging message. The message will be discarded if the UE cannot find its identity otherwise it will response by initiating random access response.
A paging cycle for a UE can range from once per 256 up to once per 32 frames, whereas in which frame it is supposed to wake up is determined by an equation that includes the identity of the terminal. From a network standpoint, paging may be transmitted more often than once per 32 frames, although not all UEs can be paged at all paging occasions since they are distributed across possible paging instances.
Paging of a UE in Evolved Packet System (EPS) is initiated from the core network, typically triggered by arrival of downlink user data. The user data to be delivered is buffered in the Serving Gateway (SGW)), which sends a Downlink Data Notification GPRS Tunneling Protocol (GTPv2-C) message to the Mobility Management Entity (MME). The MME checks which eNBs that have cells belonging to any of Tracking Areas (TAs) whose Tracking Area Identities (TAIs) are included in a UE's current TAI list and sends a PAGING S1 Application Protocol message (S1AP) message across the S1 interface to each of these eNBs, requesting the eNB to page the UE in all cells belonging to any of the concerned TAs, i.e. all cells having a TAI that is included in the UE's list of TAIs. The PAGING S1AP message includes a UE identifier based on the International Mobile Subscriber Identity (IMSI) in the UE Identity Index Value Information Element (IE), the UE's list of TAIs in the List of TAIs IE and a possible UE specific Discontinuous Reception (DRX) cycle length in the Paging DRX IE.
Upon reception of the PAGING S1AP message from the MME, the eNB calculates the applicable paging occasions, awaits the next paging occasion and sends a Radio Resource Control (RRC) message, indicated by a DL resource assignment addressed to a paging Radio Network Temporary Identifier (RNTI) on the Physical Downlink Control Channel (PDCCH), to the UE in the subframe corresponding to the paging occasion. The eNB does this for each of its cells that take part in the paging procedure.
It is expected that there will be a very large number of machine-type-communication (MTC) devices in future wireless “Networked society” scenarios. Many such devices will transmit small amount of UL data (e.g. 100 bits) infrequently (e.g. once per hour). In LTE there are plans of introducing a new solution for “low cost/complexity UEs” to target low end applications which only require low data rates. Considering that low average revenue per user is expected, these applications can be utilized over the GSM/GPRS radio interface. As more MTC UEs are deployed, this would require operators to maintain multiple radio access technologies in case there is not enough motivation for MTC UE suppliers to provide modules supporting the LTE radio interface. This would prevent operators to utilize their spectrums efficiently. Therefore, it is necessary to provide the necessary tools for the MTC UE vendors to be able to migrate the low-end MTC UEs from GSM/GPRS networks to LTE networks.